Transmission apparatus, transmission method, reception apparatus, reception method, and transmission/reception system

ABSTRACT

This technology is to enable high quality audio reproduction on the reception side without supplying a transmission clock using a clock signal line from the reception side to the transmission side. The transmission apparatus receives encoded data capable of clock recovery from a reception apparatus (external device), generates an audio clock on the basis of a carrier clock recovered from the encoded data, and transmits audio data to the reception apparatus in synchronization with the audio clock. The reception apparatus transmits the encoded data capable of clock recovery to the external device in synchronization with the carrier clock generated on the basis of an self-generating audio clock, receives the audio data from the transmission apparatus (external device), and processes the audio data on the basis of the self-generating audio clock.

CROSS REFERENCE TO PRIOR APPLICATION

This application is a National Stage Patent Application of PCTInternational Patent Application No. PCT/JP2017/010808 (filed on Mar.16, 2017) under 35 U.S.C. § 371, which claims priority to JapanesePatent Application No. 2016-066923 (filed on Mar. 29, 2016), which areall hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present technology relates to a transmission apparatus, atransmission method, a reception apparatus, a reception method, and atransmission/reception system, and more particularly relates to atransmission apparatus or the like that enables high quality audioreproduction on the reception side.

BACKGROUND ART

For example, Patent Document 1 proposes a technique in which atransmission clock is supplied from a reception side to a transmissionside using a clock signal line, and then audio data is transmitted fromthe transmission side to the reception side in synchronization with anaudio clock obtained by dividing the transmission clock so as to enablehigh quality audio reproduction on the reception side.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-074547

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present technology aims to enable high quality audio reproduction onthe reception side without supplying the transmission clock using theclock signal line from the reception side to the transmission side.

Solutions to Problems

A concept of the present technology is a transmission apparatus is atransmission apparatus including:

an encoded data reception unit that receives encoded data capable ofclock recovery from an external device;

an audio clock generator that generates an audio clock on the basis of acarrier clock recovered from the received encoded data; and

an audio data transmission unit that transmits the audio data to theexternal device in synchronization with the generated audio clock.

In the present technology, encoded data is received from an externaldevice by the encoded data reception unit. This encoded data is capableof clock recovery. For example, encoded data capable of clock recoverymay be encoded data of 8B10B coding.

An audio clock is generated by the audio clock generator on the basis ofa carrier clock (transmission clock) recovered from the received encodeddata. For example, the audio clock generator may generate the audioclock by dividing the carrier clock on the basis of dividing ratioinformation obtained from the received encoded data. In this case, thedivision is performed on the basis of the dividing ratio informationtransmitted from, the external device, making it possible to easily andproperly generate the audio clock.

Audio data is transmitted to the external device by the audio datatransmission unit in synchronization with the generated audio clock. Forexample, the audio data transmission unit may transmit the audio data tothe external device through a first physical channel, and the encodeddata reception unit may receive the encoded data from the externaldevice through a second physical channel. In this case, for example,each of the first physical channel and the second physical channel maybe a physical channel using an optical cable.

In this manner, according to the present technology, audio data istransmitted to an external device in synchronization with the audioclock generated on the basis of the carrier clock recovered from thereceived encoded data. Therefore, it is possible to perform high qualityaudio reproduction in an external device without supplying atransmission clock using a clock signal line from the external device.

Note that in the present technology when a request for using the audiocloak generated from the recovered carrier clock can be obtained forexample, the audio clock generator may generate an audio clock on thebasis of the carrier clock recovered from the encoded data, and theaudio data transmission unit may transmit the audio data to the externaldevice in synchronization with the generated audio clock. With executionof the transmission processing of the audio data based on the audioclock generated from the recovered carrier clock in response to therequest from the external device in this manner, the transmissionprocessing can be effectively performed.

Furthermore, another concept of the present technology is a receptionapparatus including:

an audio clock generator that generates an audio clock;

an encoded data transmission unit that transmits encoded data capable ofclock recovery in synchronization with a carrier clock generated on thebasis of the generated audio clock to an external device;

an audio data reception unit that receives audio data from the externaldevice; and

an audio data processing unit that processes the received audio data onthe basis of the generated audio clock.

In the present technology, an audio clock is generated by the audioclock generator. Encoded data capable of clock recovery insynchronization with the carrier clock generated on the basis of thegenerated clock is transmitted to the external device by the encodeddata transmission unit.

Audio data is received from the external device by the audio datareception unit. The audio data processing unit processes the receivedaudio data on the basis of the audio clock generated by the audio clockgenerator. For example, the audio data reception unit may receive theaudio data from the external device through a first physical channel,and the encoded data transmission unit may transmit the encoded data tothe external device through a second physical channel. In this case, forexample, each of the first physical channel and the second physicalchannel may be a physical channel using an optical cable.

In this manner, according to the present technology, encoded datacapable of clock recovery is transmitted to an external device insynchronization with a carrier clock generated on the basis of thegenerated audio clock, and audio data received from the external deviceis processed on the basis of the audio cock. Therefore, it is possibleto perform high quality audio reproduction without supplying atransmission clock using a clock signal line to an external device.

Note that it is also allowable in the present technology to configuresuch that the encoded data includes encoded data of dividing ratioinformation for obtaining the audio clock from the carrier clock, forexample. With this encoded data included, the external device can obtainthe audio clock by performing division on the carrier clock recoveredfrom the encoded data on the basis of the dividing ratio information,making it possible to generate the audio clock easily and appropriately.

Furthermore, it is allowable in the present technology to configure suchthat the encoded data includes encoded data of a request for using anaudio clock generated on the basis of the carrier clock, for example.With this encoded data included, the external device can effectivelyperform the transmission processing of the audio data based on the audioclock generated by division of the recovered carrier clock.

Effects of the Invention

According to the present technology, it is possible to achieve highquality audio reproduction on the reception side without supplying thetransmission clock using the clock signal line from the reception sideto the transmission side Effects described here in the presentspecification are provided for purposes of exemplary illustration andare not intended to be limiting. Still other additional effects may alsobe contemplated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an outline of an AV transmissionsystem as an embodiment.

FIG. 2 is a diagram illustrating a sequence of transition from a normalmode to an option mode in audio data transmission.

FIG. 3 is a block diagram illustrating a configuration example of aportion related to audio data transmission in a transmitter and areceiver in an option mode.

FIG. 4 is a diagram illustrating a structural example of a lane frame.

FIG. 5 is a block diagram illustrating a configuration example of atransmission unit and a reception unit.

FIG. 6 is a block diagram illustrating a configuration example of ascrambler.

FIG. 7 is a block diagram illustrating a circuit configuration exampleof an 8B/10B encoder and 8B/10B decoder.

FIG. 8 is a block diagram illustrating a configuration example of aclock and data recovery circuit.

FIG. 9 is a block diagram illustrating a configuration example of anaudio clock recovery unit.

FIG. 10 is a block diagram illustrating a configuration example of acarrier clock generator.

FIG. 11 is a block diagram illustrating a configuration example of adisc player as a specific example of a transmitter.

FIG. 12 is a block diagram illustrating a configuration example of atelevision receiver as a specific example of a receiver.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention (hereinafter,embodiment(s)) will be described. Note that the description will begiven in the following order.

1. Embodiments

2. Modifications

1. Embodiments

[Configuration of AV Transmission System]

FIG. 1 illustrates an outline of an audio and visual (AV) transmissionsystem 10 as an embodiment. The AV transmission system 10 includes amain stream link 60 and a sub stream link 70.

In the main stream link 60, mainly audio/video signals are transmitted.A plurality streams of transmitted video and audio, accompanyingmetadata or the like, are packed for individual streams by a datapacking unit (Data Packing) 601. Furthermore, the dividing ratios forthe recovery of the video and audio clocks from the carrier clock arerespectively generated as video clock recovery information (VCR) andaudio clock recovery information (ACR) by a VCR/ACR generator (VCR/ACRgen) 602.

A lane frame containing packed transmission data and generated recoveryinformation is generated by a frame generator 603. The lane framesobtained by the frame generator 603 of a plurality of systems aregrouped together by a multi-stream constructor 604, and further mappedto individual physical channels by a channel mapper 605 to betransmitted.

Lane frames transmitted on individual physical channels are de-mapped bya channel de-mapper 606, and further de-constructed into lane frames ofa plurality of systems by a multi-stream de-constructor 607. Then, apacket including video, audio, accompanying metadata or the like isretrieved from the lane frame by a packet generator 608 in each of thesystems.

A data de-packing unit (Data De-Packing) 609 extracts video, audio,accompanying metadata or the like from packets containing video, audio,accompanying metadata, or the like. Furthermore, in the video/audioclock unit (Video/Audio Clock) 610, recovery information (VCR and ACR)is extracted from the packet including the recovery information, and therecovery information is used to recover the video and audio clocks.

Meanwhile, in the sub stream link 70, control information or the like,that is, a control signal (Control) Ethernet data (IP data), plug andplay data (PnP neg), or the like, are transmitted bidirectionally.Control information or the like is packed in data packing units (DataPacking) 701 a and 701 b. A lane frame containing packed controlinformation is generated by frame generators 702 a and 702 b andtransmitted via the physical channels.

Packet generators 703 a and 703 b retrieve packets containing a controlsignal (Control), Ethernet data (IP data), plug and play data (PnP neg)and the like from the lane frame transmitted via the physical channel.Then, data de-packing units (Data De-Packing) 704 a and 704 b extractscontrol signal (Control), Ethernet data (IP data), plug and play data(PnP neg) or the like from the packet that has been retrieved.

The transmission of audio data in the AV transmission system 10 isnormally processed by operation in the normal mode as described below.That is, audio data is transmitted from the transmitter to the receiverby the main stream link in synchronization with the audio clockgenerated in the transmitter, and together with this, the dividingration information (recovery information) for recovery of an audio clockfrom the carrier clock of the main stream link is transmitted by themain stream link. The receiver uses the dividing ratio indicated by thedividing ratio information to recover the audio clock from the carrierclock of the main stream link, and this audio clock is used to processthe audio data.

In the present embodiment, in a case where there is a request from thereceiver to the transmitter, option mode operation as below is performedin association with the transmission of audio data in the AVtransmission system 10. That is, the transmitter divides the carrierclock of the sub stream link of the receiver to generate an audio clock,and audio data is transmitted by the main stream link in synchronizationwith this audio clock. The receiver processes the received audio data onthe basis of the audio clock generated within the receiver. With thisoption mode operation, it is possible to reproduce high quality audio onthe receiver.

FIG. 2 illustrates a sequence diagram at the time of transition from thenormal mode to the option mode in association with transmission of audiodata. The receiver use the sub stream link to transmit to thetransmitter an audio clock master switch (ACMSW) packet unit on which anaudio master clock (AMCLK) switch request representing a switch requestto the option mode with the audio clock on the receiver side as amaster.

In a case where the request can be handled, the transmitter thatreceived the ACMSW packet unit generates an audio clock on the basis ofthe dividing ratio information (ACR information) stored in the ACMSWpacket unit from the carrier clock of the sub stream link of thereceiver as an audio clock, then, switches to an audio data transmissionstate in synchronization with this audio clock, and returns an ACKcommand to the receiver by a sub stream link. After reception of the ACKcommand, the receiver switches the audio clock to the audio clockgenerated in the receiver, and performs reproduction of the audio.

FIG. 3 illustrates a configuration example of a portion related to audiodata transmission of a transmitter 300 and a receiver 400 in theabove-described option mode. The transmitter 300 includes an audiosource 301, a FIFO memory unit 302, an audio sample packet unit (ASPU)generator 303, an ancillary audio data packet unit (AAPU) generator 304,a lane frame generator 305, and a transmission unit 306 of the mainstream link. Furthermore, the transmitter 300 further includes areception unit 307 of the sub stream link, a lane frame decoding unit309, an ACMSW decoding unit 310, and an audio clock recovery unit(Re-gen Audio Clock) 311.

The receiver 400 includes a reception unit 401 of the main stream link,a lane frame decoding unit 402, an ASPU decoding unit 403, an AAPUdecoding unit 404, and an audio decoding unit 405. Furthermore, thereceiver 400 includes an audio clock source 406, a lane clock generator407, an ACMSW generator 408, a lane frame generator 409, a transmissionunit 410 of the sub stream link.

The audio source 301 outputs uncompressed or compressed audio data(audio sample data) as audio data as transmission target, and outputsaudio additional information at the same time. The audio additionalinformation includes information such as sampling frequency, samplesize, and an encoding method (uncompressed, compression method). TheFIFO memory unit 302 inputs the audio data as transmission target outputfrom the audio source 301, and outputs the audio data in synchronizationwith the audio clock recovered by the audio clock recovery unit 311.

The ASPU generator 303 packs audio data input in synchronization withthe audio clock from the FIFO memory unit 302, and generates an ASpacket unit (ASPU) having audio data inserted in a payload. The AAPUgenerator 304 packs audio additional information output from the audiosource 301, and generates an AA packet unit (AAPU) having audioadditional information inserted in a payload.

The lane frame generator 305 generates a lane frame containing an ASpacket unit generated by the ASPU generator 303, an AA packet unitgenerated by the AAPU generator 304, or the like, as a payload unit.

FIG. 4 illustrates a structural example of a lane frame. The structureof the lane frame is a collection of structures referred to as units.The lane frame includes 6000 units, for example, including: a headerunit containing attributes and synchronization information of the laneframe; and a payload unit storing individual data. Each of the units hasa fixed length and has a special code referred to as a delimiter in thefirst two bytes and the last byte. A reception side lane frame decoder(Lane Frame dec) can determine the content of each of the payload unitsby the content of the delimiter.

Examples of the payload unit include the AS packet unit (ASPU) and theAA packet unit (AAPU) transmitted on the main stream link, and inaddition to this, a sub stream packet unit (SSPU) for bidirectionallytransmitting a control signal on the sub stream link, and the like.

Returning to FIG. 3, the transmission unit 306 transmits the lane frameof the main stream link generated by the lane frame generator 305electrically or optically—optically using an optical cable in thepresent embodiment—to the receiver 400 by the main stream link.

FIG. 5(a) illustrates a configuration example of the transmission unit306. The transmission unit 306 includes a scrambler 511, an 8B/10Bencoder (8b/10b Encode) 512, a serializer 513, a laser diode driver 514,and a laser diode 515.

The data of the lane frame output from the lane frame generator 305 isinput to the scrambler 511. The scrambler 511 scrambles data of the laneframe. In this case, the data of the lane frame is rearranged randomly,and the continuity of the data is removed. This scrambling achieves dataretention in an AC coupling transmission line and also suppressesunnecessary radiation in the physical channel.

The scrambler 511 is formed with linear feedback shift register having afeedback path based on a certain generator polynomial, and takes anexclusive OR (XOR) with input data (data input) so as to outputconverted scrambled data. FIG. 6 illustrates a configuration example ofthe scrambler 511. In the illustrated example, the generation other rowformula is “G(x)=x{circumflex over ( )}16+x{circumflex over( )}5+x{circumflex over ( )}4+x{circumflex over ( )}3+1” with linearfeedback shift register of 16 bits.

Returning to FIG. 5(a), data output from the scrambler 511 is input tothe 8B/10B encoder 512. The 8B/10B encoder 512 performs encodeprocessing of 8B10B coding on input data. In this case, the 8-bit datais converted into 10-bit data to ensure the frequency of change of thedata so as to enable elimination of the DC component of the data to betransmitted and extraction of reception clock from reception data at thereception circuit.

FIG. 7(a) illustrates a circuit configuration example of the 8B/10Bencoder 512. In this case, the input data (Transmit) from the scrambler511 is input to an encoder (8b→10b Encode) as 9-bit data including acontrol bit (Z), and then, output as 10-bit data. Here, fixed data forsynchronization referred to as a control symbol may be inserted asappropriate.

Returning to FIG. 5(a), the data output from the 8B/10B encoder 512 isinput to the serializer 513. The serializer 513 converts input data fromparallel data to serial data. Note that the 8B/10B encoder 512 describedabove performs encode processing of 8B10B coding on data to enable thebyte delimiter of each of data to be easily recognized by the receptioncircuit.

Data output from the serializer 513 is input to the laser diode driver514. The laser diode driver 514 drives the laser diode 515 on the basisof the input data and causes the laser diode 515 to output an opticalsignal to be transmitted on the main stream link.

The reception unit 307 receives the lane frame of the sub stream Linktransmitted electrically or optically—optically using an optical cablein the present embodiment—from the receiver 400 by the sub stream link.

FIG. 5(b) illustrates a configuration example of the reception unit 307.The reception unit 307 includes a photodetector (Photo Detector) 521, anamplifier (Trans impedance Amplifier) 522, a de-serializer(De-Serializer) 523, an 8B/10B decoder (8b/10b Decode) 524, and adescrambler 525.

The optical signal transmitted on the sub stream link is input to thephotodetector 521 and converted into an electric signal. This electricsignal is amplified by the amplifier 522. Data (electric signal) outputfrom the amplifier 522 is input to the de-serializer 523. Thede-serializer 523 converts the input data from serial data to paralleldata.

Note that this de-serializer 523 includes a clock and data recoverycircuit (CDR) 308 in a preceding stage, recovers the carrier clock (laneclock) from the input data from the amplifier 522, and receives datareliably on the basis of the carrier clock.

FIG. 8 illustrates a configuration example of the clock and datarecovery circuit 308. Serial data (Serial Data Input) as input data fromthe amplifier 522 is supplied to a phase frequency detector 308 a. Aphase locked loop (PLL) circuit is formed with a phase frequencydetector 308 a, a loop filter 308 b, and a voltage controlled oscillator(VCO) 308 c.

The clock (Recovery Clock) obtained by the voltage controlled oscillator308 c is phase-compared with serial data (Serial Data Input), that is,input data from the amplifier 522 by the phase frequency detector 308 a.An obtained comparison error signal is supplied from the loop filter 308b as a voltage control signal Vcon to the voltage controlled oscillator308 c. As a result, the clock (Recovery Clock) obtained by the voltagecontrolled oscillator 308 c synchronized with input data from theamplifier 522.

Furthermore, serial data (Serial Data Input) as input data from theamplifier 522 is input to the data register 308 d and latched by theclock (Recovery clock) obtained by the voltage controlled oscillator 308c. With this operation, data synchronized with the clock (Recoveryclock) obtained by the voltage controlled oscillator 308 c is obtainedas the output data of the data register 308 d.

Returning to FIG. 5(b), the data output from the de-serializer 523 isinput to the 8B/10B decoder 524. The 8B/10B decoder 524 applies decodeprocessing of 8B10B coding on the input data to obtain 8-bit data.

FIG. 7(b) illustrates an example of a circuit configuration of the8B/10B decoder 524. In this case, the configuration is reversearrangement of the 8B/10B encoder 512 in FIG. 7(a), in which the 10-bitdata from the de-serializer 523 is input to the decoder (10b→8b Decode)and output as 9-bit data containing a control hit (Z).

Returning to FIG. 5(b), the data output from the 8B/10B decoder 524 isinput to the descrambler 525. The descrambler 525 performs descramblingthat is reverse of that performed in the scrambler 511 of thetransmission unit 306, and outputs lane frame data.

Returning to FIG. 3, the lane frame decoding unit 309 retrieves apayload unit contained in the lane frame received by the reception unit307, here, an ACMSW packet unit. The ACMSW decoding unit 310 obtainsdividing ratio information (ACR information) stored in the ACMSW packetunit retrieved by the lane frame decoding unit 309. This dividing ratioinformation includes two values, Maud and Naud.

The audio clock recovery unit 311 recovers an audio clock from thecarrier clock (Lane Clock) recovered by the CDR 308 of the receptionunit 307 and from Maud and Naud. In this case, a 1.215 GHz carrier clock(Lane Clock) is divided to generate a 270 MHz video clock (Link VideoClock), for example, and then, the audio clock (Audio Clock) isrecovered from this video clock (Link Video Clock) and Maud and Naud. Aswill be described below in detail, Naud is defined as a count intervalof an audio clock, while Maud is defined as a count value of a videoclock (Link Video Clock) at that interval.

Here, there is a relationship of the following formula (1) between thecarrier clock (Lane Clock) and the video clock (Link Video Clock).Furthermore, there is a relationship of the following formula (2)between the audio clock, the video clock (Link Video Clock), and Maudand Naud.Link Video Clock× 9/2×10=Lane Clock  (1)Audio Clock×Maud=Link Video Clock×Naud  (2)

An example of the combination of Maud and Naud is as follows. That is,Maud=61875, Naud=5632 in a case where Audio Clock=24.5760 MHz (samplingfrequency=192 kHz).

FIG. 9 illustrates a configuration example of the audio clock recoveryunit 311. The carrier clock (Lane Clock) is divided by 1/10 by thedivider 311 a, and its output clock is further divided by 2/9 by thedivider 311 b, leading to acquisition of a video clock (Link VideoClock). Then, the clock obtained by 1/Maud division of the video clock(Link Video Clock) by the divider (Divide by Maud) 311 c and the clockobtained by 1/Naud division of the output clock from the PLL circuit 311d by the divider (Divide by Naud) 311 e are input to the PLL circuit 311d to undergo phase comparison, leading to acquisition of an audio clockas an output clock from the PLL circuit 311 d.

Returning to FIG. 3, the reception unit 401 receives the lane frametransmitted electrically or optically—optically using an optical cablein the present embodiment—from the transmitter 300 by the main framelink. Although detailed description is omitted, the reception unit 401is configured similarly to the reception unit 307 in the transmitter 300(refer to FIG. 5(b)).

The lane frame decoding unit 402 applies decode processing on the laneframe received by the reception unit 401 and extracts an AS packet unit(ASPU) and an AA packet unit (AAPU). As described above, the AS packetunit is a unit packet having audio data inserted in a payload, and theAA packet unit is a packet unit having audio additional informationinserted in a payload.

The ASPU decoding unit 403 applies decode processing on the AS packetunit extracted by the lane frame decoder 402 and extracts audio data.The AAPU decoding unit 404 applies decode processing on the AA packetunit extracted by the lane frame decoder 402 and extracts audioadditional information.

The audio clock source 406 generates an audio clock. The audio decodingunit 405 processes audio data retrieved by the ASPU decoding unit 403 insynchronization with the audio clock generated by the audio clock source406 on the basis of the audio additional information retrieved by theAAPU decoding unit 404 so as to obtain output audio data for soundoutput. Then, the audio decoding unit 405 outputs the output audio datain synchronization with the audio clock generated by the audio clocksource 406.

A carrier clock (Lane Clock) generator 407 generates a carrier clock(lane clock) of 1.215 GHz on the basis of an audio clock and a videoclock (Link Video Clock) of 270 MHz, and also outputs the two valuesMaud and Naud as dividing ratio information. Here, Naud is defined as acount interval of an audio clock, while Maud is defined as a count valueof a video clock (Link Video Clock) at that interval.

FIG. 10 illustrates a configuration example of the carrier clockgenerator 407. The counting unit 407 b functions as a Naud advancingcounter based on the value of Naud generated by the Naud generator 407a, and performs counting operation using the audio clock as the countclock. The carry output of the counting unit 407 b is supplied to thecounting unit 407 c as a reset signal, and is also supplied as a latch(hold) signal to the latch unit 407 d.

The counting unit 407 c is reset by the carry output of the countingunit 4071 and performs counting operation using the 270 MHz video clock(Link Video Clock) as the count clock. The count output of the countingunit 407 c is input to the larch unit 407 d. The latch unit 407 d holdsthe count output of the counting unit 407 c by the carry output of thecounting unit 407 b and obtains the value of Maud.

A multiplier 407 e multiplies the 270 MHz video clock (Link Video Clock)by 9/2. Furthermore, the multiplier 407 f multiplies the output clock ofthe multiplier 407 e by ten to obtain a carrier clock (Lane Clock) of1.215 GHz.

The carrier clock generator 407 outputs a 1.215 GHz carrier clock (LaneClock) obtained by the multiplier 407 f, and also outputs the value ofNaud generated by the Naud generator 407 a and the value of Maud held bythe latch unit 407 d. In this case, the carrier clock (Lane Clock) andthe video clock (Link Video Clock) satisfy the relationship of the aboveformula (1). Furthermore, the audio clock (Audio Clock), the video clock(Link Video Clock), and Maud and Naud satisfy the relationship of theabove formula (2).

Returning to FIG. 3, the ACMSW generator 408 generates an audio clockmaster switch (ACMSW) packet unit as an SS packet unit. The ACMSW packetunit includes an audio master clock switch request (AMCLK) indicating aswitch request to an option mode with the audio clock on the side of thereceiver 400 as a master, and also includes Maud and Naud as dividingratio information output from the carrier clock generator 407.

The lane frame generator 409 generates a lane frame including the SSpacket unit such as the ACMSW packet unit generated by the ACMSWgenerator 408 as a payload unit (refer to FIG. 4).

The transmission unit 410 transmits the lane frame of the sub streamlink generated by the lane frame generator 409 electrically oroptically—optically using an optical cable in the present embodiment—tothe transmitter 300 by the sub stream link. The transmission unit 410 isconfigured similarly to the transmission unit 306 in the transmitter 300(refer to FIG. 5(a)). In this case, output data from the 8B/10B encoder512 is converted from parallel data to serial data by the serializer513, and then, the serial data is transmitted as an optical signal insynchronization with the carrier clock.

Operation of portions related to the audio data transmission of thetransmitter 300 and the receiver 400 illustrated in FIG. 3 will bebriefly described. The audio clock generated by the audio clock source406 of the receiver 400 is supplied to the carrier clock generator 407.Furthermore, a 270 MHz video clock (Link Video Clock) is supplied to thecarrier clock generator 407. A carrier clock generator 407 generates acarrier clock (Lane Clock) of 1.215 GHz on the basis of an audio clockand a video clock (Link Video Clock) of 270 MHz, and also obtains Maudand Naud as dividing ratio information (refer to FIG. 10).

Maud and Naud as the dividing ratio information obtained by the carrierclock generator 407 are supplied to the ACMSW generator 408. The ACMSWgenerator 408 generates an ACMSW packet unit as an SS packet unit. TheACMSW packet unit includes AMCLK indicating a switch request to anoption mode with the audio clock on the side of the receiver 400 as amaster, and also includes Maud and Naud as dividing ratio informationoutput from the carrier clock generator 407.

The ACMSW packet unit generated by the ACMSW generator 408 is suppliedto the lane frame generator 409. The lane frame generator 409 generatesa lane frame including an SS packet unit such as an ACMSW packet unit asa payload unit (refer to FIG. 4).

The lane frame of the sub stream link generated by the lane framegenerator 409 is supplied to the transmission unit 410. The transmissionunit 410 optically transmits the lane frame of the sub stream link tothe transmitter 300 using an optical cable (refer to FIG. 5(a)). In thiscase, the transmission data is transmitted as an optical signal insynchronization with the carrier clock.

The reception unit 307 of the transmitter 300 receives a lane frame of asub stream link optically transmitted from the receiver 400 using anoptical cable by the sub stream link (refer to FIG. 5(b)). The receptionunit 307 causes the clock and data recovery circuit 308 included in thepreceding stage of the de-serializer 613 to recover the carrier clock(Lane Clock) from the input data from the amplifier 612, and reliablyreceives data on the basis of this carrier clock.

The lane frame of the sub stream link received by the reception unit 307is supplied to the lane frame decoding unit 309. The lane frame decodingunit 309 applies decode processing on the lane frame of the sub streamlink, and retrieves an SS packet unit included in the lane frame, hereinthe ACMSW packet unit.

The ACMSW packet unit retrieved by the lane frame decoding unit 309 issupplied to the ACMSW decoding unit 310. The ACMSW decoding unit 310applies decode processing on the ACMSW packet unit, and obtains AMCLKindicating a switch request to an option mode with the audio clock onthe receiver 400 side defined as a master stored in the ACMSW packetunit, and obtains Maud and Naud as the dividing ratio information.

In a case where the switch request represented by AMCLK can be handledon the transmitter 300 side, audio clock is recovered on the basis ofthe carrier clock (Lane Clock) recovered by the clock and data recoverycircuit 308 and Maud and Naud as dividing ratio information obtained bythe ACMSW decoding unit 310, leading to a state of transmitting audiodata in synchronization with the recovered audio clock.

In this case, the carrier clock (Lane Clock) recovered by the clock anddata recovery circuit 308 and Maud and Naud as the dividing ratioinformation obtained by the ACMSW decoding un 310 are supplied to theaudio clock recovery unit 311. The audio clock recovery unit 311recovers an audio clock from the carrier clock (Lane Clock), Maud andNaud (refer to FIG. 9).

The uncompressed or compressed audio data (audio sample data) outputfrom the audio source 301 is input to the FIFO memory unit 302. The FIFOmemory unit 302 sequent ally outputs audio data input from the audiosource 301 in synchronization with the audio clock recovered by theaudio clock recovery unit 311.

The audio data output from the FIFO memory unit 302 is supplied to theASPU generator 303. The ASPU generator 303 packs this audio data togenerate an AS packet unit (ASPU) having audio data inserted in thepayload. This AS packet unit is supplied to the lane frame generator305.

Furthermore, the audio additional information output from the audiosource 301 is supplied to the AAPU generator 304. The AAPU generator 304performs packing of this audio additional information and generates anAA packet unit having audio additional information inserted in thepayload. The audio additional information includes information such assampling frequency, sample size, and an encoding method (uncompressed,compression method). This AA packet unit is supplied to the lane framegenerator 305.

The lane frame generator 305 generates a lane frame containing an ASpacket unit, an AA packet unit, or the like, as a payload unit. The laneframe of the sub stream link generated by the lane frame generator 305is supplied to the transmission unit 306. The transmission unit 306optically transmits the lane frame of the main stream link to thereceiver 400 using an optical cable (refer to FIG. 5(a)).

As described above, in a case where the switch request represented byAMCLK can be handled on the transmitter 300 side, audio clock isrecovered on the basis of the carrier clock (Lane Clock) recovered bythe clock and data recovery circuit 308 and Maud and Naud as dividingratio information obtained by the ACMSW decoding unit 310, leading to astate of transmitting audio data in synchronization with the recoveredaudio clock.

In this case, an ACK command is returned from the transmitter 300 sideto the receiver 400 side by the sub stream link. Then, on the receiver400 side, the audio clock is switched to a state using an audio clockgenerated from the audio clock source 406 as an audio clock.

The reception unit 401 of the receiver 400 receives a lane frame of amain stream link optically transmitted from the transmitter 300 using anoptical cable by the main stream link (refer to FIG. 5(b)). The laneframe of the main stream link is supplied to the lane frame decodingunit 402.

The lane frame decoding unit 402 applies decode processing on the laneframe of the main stream link, and extracts the AS packet unit (ASPU)and the AA packet unit (AAPU) contained in the lane frame. As describedabove, audio data is inserted in the AS packet unit, and audioadditional information is inserted in the AA packet unit.

The AS packet unit extracted by the lane frame decoding unit 402 issupplied to the ASPU decoding unit 403. The ASPU decoding unit 403applies decode processing on the AS packet unit, to allow the audio datato be retrieved. Furthermore, the AA packet unit extracted by the laneframe decoding unit 402 is supplied to the AAPU decoding unit 404. TheAAPU decoding unit 404 applies decode processing on the AA packet unitto allow the audio additional information to be retrieved.

The audio data (audio sample data) retrieved by the ASPU decoding unit403 and the audio additional information retrieved by the AAPU decodingunit 404 are supplied to the audio decoding unit 405. The audio decodingunit 405 processes audio data in synchronization with the audio clockgenerated by the audio clock source 406 on the basis of the audioadditional information so as to obtain output audio data for soundoutput. Then, the audio decoding unit 405 outputs the output audio datain synchronization with the audio clock generated by the audio clocksource 406.

[Configuration Example of Disc Player]

FIG. 11 illustrates a configuration example of a disc player 11 as aspecific example of the transmitter 300. The disc player 11 includes amain stream link transmission unit 125, a sub stream link transmissionunit 126, and a sub stream link reception unit 127.

The main stream link transmission unit 125 includes processing unitscorresponding to the FIFO memory unit 302, the ASPU generator 303, theAAPU generator 304, the lane frame generator 305, the transmission unit306, or the like, in the transmitter 300 of FIG. 3. The sub stream linkreception unit 127 includes processing units corresponding to thereception unit 307, the lane frame decoding unit 309, the ACMSW decodingunit 310, the audio clock recovery unit 311, or the like, in thetransmitter 300 in FIG. 3.

Furthermore, the disc player 11 includes a central processing unit (CPU)104, an internal bus 105, a flash read only memory (ROM) 106, asynchronous random access memory (SDRAM) 107, a remote control receptionunit 108, and a remote control transmitter 109.

Furthermore, the disc player 11 includes a serial advanced technologyattachment (SATA) interface 110, a blu-ray disc (BD) drive 111, anEthernet interface (Ethernet I/F) 112, and a network terminal 113.Furthermore, the disc player 11 includes a moving picture expert group(MPEG) decoder 115, a graphic generation circuit 116, a video outputterminal 117, and a sound output terminal 118.

Furthermore, the disc player 11 may include a display control unit 121,a panel drive circuit 122, a display panel 123, and a power supply unit124. Note that “Ethernet” is a registered trademark. The CPU 104, theflash ROM 106, the SDRAM 107, the SATA interface 110, the Ethernetinterface 112, the MPEG decoder 115, and the display control unit 121are connected to the internal bus 105.

The CPU 104 controls operation of individual portions of the disc player11. The flash ROM 106 stores control software and data. The SDRAM 107constitutes a work area of the CPU 104. The CPU 104 develops thesoftware and data read from the flash ROM 106 onto the SDRAM 107 tostart the software, and controls individual portions of the disc player11.

The remote control reception unit 108 receives a remote control signal(remote control code) transmitted from the remote control transmitter109, and supplies the received signal to the CPU 104. The CPU 104controls individual portions of the disc player 11 in accordance withremote control codes. Note that while the present embodiment illustratesa case where a user instruction input unit is represented by a remotecontrol unit, the user instruction input unit may use anotherconfiguration, for example, a switch, a wheel, a touch panel unit onwhich instructions are input by proximity/touch, a mouse, a keyboard, agesture input unit that detects an instruction input by a camera, and asound input unit for inputting instruction by sound, or the like.

The BD drive 111 records content data on a BD disc (not illustrated) asa disc-shaped recording medium or reproduces content data from this BD.The BD drive 111 is connected to the internal bus 105 via the SATAinterface 110. The MPEG decoder 115 applies decode processing on an MPEG2 stream reproduced by the BD drive 111 to obtain image and sound data.

In transmitting image and sound data from the disc player 11 to anexternal device (receiver), image and sound data are supplied from, theMPEG decoder 115 to the main stream link transmission unit 125. In thiscase, the image and sound data may be either compressed data oruncompressed data. In this case, the MPEG decoder 115 constitutes theaudio source 301 in a portion related to audio data transmission in FIG.3.

The graphic generation circuit 116 superimposes graphic data on imagedata obtained by the MPEG decoder 115 as necessary, for example. Thevideo output terminal 117 outputs the image data output from the graphicgeneration circuit 116. The sound output terminal 118 outputs the sounddata obtained by the MPEG decoder 115.

The panel drive circuit 122 drives the display panel 123 on the basis ofthe video (image) data output from the graphic generation circuit 260.The display control unit 121 controls the graphics generation circuit116 and the panel drive circuit 122 to control the display on thedisplay panel 123. The display panel 123 includes a liquid crystaldisplay (LCD), a plasma display panel (PDP), an organicelectroluminescence (EL) display, and the like, for example.

Note that while the present embodiment illustrates an example having thedisplay control unit 121 in addition to the CPU 104, the display of thedisplay panel 123 may be directly controlled by the CPU 104.Furthermore, the CPU 104 and the display control unit 121 may beprovided in one chip or a plurality of cores. The power supply unit 124supplies power to individual portions of the disc player 11. The powersupply unit 124 may be either an AC power supply or a battery (storagebattery, dry battery).

The operation of the disc player 11 illustrated in FIG. 11 will bebriefly described. At the time of recording, content data to be recordedis obtained via a digital tuner (not illustrated) or from the networkterminal 113 via the Ethernet interface 112. This content data is inputto the SATA interface 110 and recorded on a BD by the BD drive 111. Insome cases, this content data may be recorded in a hard disk drive (HDD)(not illustrated) connected to the SATA interface 110.

At the time of reproduction, the content data (MPEG stream) reproducedfrom the BD by the BD drive 111 is supplied to the MPEG decoder 115 viathe SATA interface 110. In the MPEG decoder 115, decode processing isperformed on the reproduced content data to obtain uncompressed mage andsound data. The image data is output to the video output terminal 117through the graphic generation circuit 116. Furthermore, the sound datais output to the sound output terminal 118.

Furthermore, at the time of reproduction, the image data obtained by theMPEG decoder 115 is supplied to the panel drive circuit 122 through thegraphic generation circuit 116 according to the user operation, and thereproduced image is displayed on the display panel 123. Furthermore, thesound data obtained by the MPEG decoder 115 is supplied to a speaker(not illustrated) in accordance with user operation, and soundcorresponding to the reproduced image is output.

Furthermore, in the case of transmitting image and sound data from thedisc player 11 to an external device (receiver) at the time ofreproduction, the MPEG decoder 115 supplies image and sound data(uncompressed data or uncompressed Data) to the main stream linktransmission unit 125 so as to be transmitted to the external device(receiver) by the main stream link.

Note that when the content data reproduced by the BD drive 111 is to betransmitted to a network at the time of reproduction, the content datais output to the network terminal 113 via the Ethernet interface 112.Here, the image data may first be encrypted using a copyright protectiontechnology, for example, HDCP, DTCP, DTCP+, and the like before beingoutput.

In the option mode with the audio clock on the receiver side defined asmaster, an audio clock recovered at the sub stream link reception unit127 on the basis of the carrier clock (Lane Clock) together with Maudand Naud as the dividing ratio information is supplied to the mainstream link transmission unit 125, as illustrated by broken lines. Then,the main stream link transmission unit 125 performs transmissionprocessing on audio data (audio sample data) on the basis of therecovered audio clock.

[Exemplary Configuration of Television Receiver]

FIG. 12 illustrates a configuration example of the television receiver12 as a specific example of the receiver 400. The television receiver 12includes a main stream link reception unit 233, a sub stream linkreception unit 234, a sub stream link transmission unit 235, and anaudio clock source 236.

The main stream link reception unit 233 includes processing unitscorresponding to the reception unit 401, the lane frame decoding unit402, the ASPU decoding unit 403, the AAPU decoding unit 404, and theaudio decoding unit 405, in the receiver 400 of FIG. 3. The sub streamlink transmission unit 235 includes a lane clock generator 407, an ACMSWgenerator 408, a lane frame generator 409, the transmission unit 410 ofthe sub stream link, or the like in the receiver 400 of FIG. 3.

Furthermore, the television receiver 12 has an antenna terminal 205, adigital tuner 206, an MPEG decoder 207, a video signal processingcircuit 208, a graphic generation circuit 209, a panel drive circuit210, and a display panel 211.

Furthermore, the television receiver 12 includes a sound signalprocessing circuit 212, a sound amplification circuit 213, a speaker214, an internal bus 220, a CPU 221, a flash ROM 222, and a synchronousrandom access memory (SDRAM) 223. Furthermore, the television receiver12 includes an Ethernet interface (Ethernet I/F) 224, a network terminal225, a remote control reception unit 226, and a remote controltransmitter 227. Furthermore, the television receiver 12 also includes adisplay control unit 231 and a power supply unit 232. Note that“Ethernet” is a registered trademark.

The CPU 221 controls operation of individual portions of the televisionreceiver 12. The flash ROM 222 stores control software and data. TheSDRAM 223 constitutes a work area of the CPU 221. The CPU 221 developsthe software and data read from the flash ROM 222 onto the SDRAM 223 toactivate the software, and controls individual portions of thetelevision receiver 12.

The remote control reception unit 226 receives a remote control signal(remote control code) transmitted from the remote control transmitter227, and supplies the received signal to the CPU 221. The CPU 22 lcontrols individual portions of the television receiver 12 on the basisof this remote control code. Note that while the present embodimentillustrates a case where a user instruction input unit is represented bya remote control unit, the user instruction input unit may use anotherconfiguration, for example, a touch panel unit on which instructions areinput by proximity/touch, a mouse, a keyboard, a gesture input unit thatdetects an instruction input by a camera, and a sound input unit forinputting instruction by sound, or the like.

The network terminal 225 is a terminal connected to a network and isconnected to the Ethernet interface 224. The CPU 221, the flash ROM 222,the SDRAM 223, the Ethernet interface 224, the MPEG decoder 207, and thedisplay control unit 231 are connected to the internal bus 220.

The antenna terminal 205 is a terminal for inputting a televisionbroadcast signal received by a reception antenna (not illustrated). Thedigital tuner 206 processes the television broadcast signal input to theantenna terminal 205 and extracts a partial TS (Transport Stream) (TSpackets of video data and TS packets of sound data) from a predeterminedtransport stream corresponding to selection channel of a user

Furthermore, the digital tuner 206 retrieves program specificinformation/service information (PSI/SI) from the obtained transportstream and outputs it to the CPU 221. The processing of extracting thepartial TS of an arbitrary channel from a plurality of transport streamsobtained by the digital tuner 206 is enabled by acquisition ofinformation of the packet ID (PID) of the arbitrary channel from thePSI/SI (PAT/PMT).

The MPEG decoder 207 applies decode processing on video packetizedelementary stream (PES) packets formed with TS packets of video dataobtained by the digital tuner 206 and obtains image data. Furthermore,the MPEG decoder 207 applies decode processing on the sound PES packetformed with TS packets of sound data obtained by the digital tuner 206and obtains sound data. Furthermore, the MPEG decoder 207 applies decodeprocessing on the content data (image data and sound data) supplied fromthe network terminal 225 via the Ethernet interface 224 and obtainsimage and sound data.

The video signal processing circuit 208 and the graphic generationcircuit 209 perform scaling processing (resolution conversionprocessing) graphics data superimposition processing, or the like asnecessary on the image data obtained by the MPEG decoder 207 or theimage data received by the reception unit 233.

The panel drive circuit 210 drives the display panel 211 on the basis ofthe video (image) data output from the graphic generation circuit 209.The display control unit 231 controls the graphics generation circuit209 and the panel drive circuit 210 to control the display on thedisplay panel 211. The display panel 211 includes a liquid crystaldisplay (LCD), a plasma display panel (PDP), an organicelectroluminescence (EL) display, and the like, for example.

Note that while the present embodiment illustrates an example having thedisplay control unit 231 in addition to the CPU 221, the display of thedisplay panel 211 may be directly controlled by the CPU 221.Furthermore, the CPU 221 and the display control unit 231 may beprovided in one chip or a plurality of cores. The power supply unit 232supplies power to individual portions of the television receiver 12. Thepower supply unit 232 may be either an AC power supply or a battery(storage battery, dry battery).

The sound signal processing circuit 212 performs necessary processingsuch as D/A conversion on the sound data obtained by the MPEG decoder207 or the sound data received by the reception unit 233. The soundamplification circuit 213 amplifies the sound signal output from thesound signal processing circuit 212 and supplies the amplified signal tothe speaker 214.

Note that the speaker 214 can be either monophonic or stereophonic.Furthermore, the number of speakers 214 may be either one, or two ormore. Furthermore, the speaker 214 may be an earphone or a headphone.Furthermore, the speaker 214 may be one compatible with 2.1 channels,5.1 channels, or the like. Furthermore, the speaker 214 may be connectedto the television receiver 12 wirelessly. Furthermore, the speaker 214may be another device.

Note that when the content data received is to be transmitted to anetwork, the content data is output to the network terminal 225 via theEthernet interface 224, for example. Here, the image data may first beencrypted using a copyright protection technology, for example, HDCP,DTCP, DTCP+, and the like before being output.

Operation of the television receiver 12 illustrated in FIG. 12 will bebriefly described. The television broadcast signal input into theantenna terminal 205 is supplied to the digital tuner 206. The digitaltuner 206 processes the television broadcast signal, outputs apredetermined transport stream corresponding to selection channel of auser, extracts a partial TS (TS packets of video data and IS packets ofsound data) from the transport stream, and the partial TS is supplied tothe MPEG decoder 207.

The MPEG decoder 207 applies decode processing on a video PES packetformed with TS packets of video data to obtain video data. This videodata undergoes scaling processing (resolution conversion processing),graphics data superimposition processing or the like in the video signalprocessing circuit 208 and the graphic generation circuit 209 asnecessary and is supplied to the panel drive circuit 210 Accordingly,the display panel 211 displays an image corresponding to the userselected channel.

Furthermore, the MPEG decoder 207 applies decode processing on the audioPES packet formed with TS packets of sound data, leading to acquisitionof sound data. This sound data undergoes necessary processing such asD/A conversion by the sound signal processing circuit 212, and isfurther amplified by the sound amplification circuit 213, and thereaftersupplied to the speaker 214. With this operation, the speaker 214outputs the sound corresponding to the user selected channel.

Furthermore, the content data (image data and sound data) supplied fromthe network terminal 225 to the Ethernet interface 224 is supplied tothe MPEG decoder 207. Thereafter, operation similar to the above ca seof receiving the television broadcast signal is performed, so as todisplay an image on the display panel 211 and output sound from thespeaker 214.

Furthermore, in a case where the television receiver 12 receives imageand sound data from an external device (transmitter), the image andsound data receiver by the main stream link reception unit 233 arerespectively supplied to the video signal processing circuit. 212 andthe sound signal processing circuit 212. Thereafter, operation similarto the above case of receiving the television broadcast signal isperformed, so as to display an image on the display panel 211 and outputsound from the speaker 214.

Furthermore, in the option mode in which the audio clock on the receiverside is defined as master, the state transitions to a state where theaudio clock generated by the audio clock source 236 is used asillustrated by the broken lines.

That is, the sub stream link transmission unit 235 generates a carrierclock (Lane Clock) on the basis of the audio clock and the video clock(Link Video Clock) generated by the audio clock source 236, whileobtains values of Maud and Naud as the dividing ratio information. Then,the sub stream link transmission unit 235 transmits the transmissiondata (serial data) of the lane frame of the sub stream link includingthe SS packet unit such as the ACMSW packet unit having the value ofMaud, Naud, in synchronization with the generated carrier clock (LaneClock).

Furthermore, the main stream link reception unit 233 processes thereceived audio data (audio sample data) in synchronization with theaudio clock generated by the audio clock source 406, leading toacquisition of output audio data for sound output.

As described above, in the AV system 10 illustrated in FIG. 1, thetransmitter 300 (refer to FIG. 3) transmits the audio data to thereceiver 400 (refer to FIG. 3) in synchronization with the audio clockobtained by dividing the carrier clock recovered from the receivedencoded data. Therefore, it is possible to perform high quality audioreproduction in the receiver 400 without supplying a transmission clockusing a clock signal line from the receiver 400.

Furthermore, in the AV system 10 illustrated in FIG. 1, the transmitter300 (refer to FIG. 3) transmits the audio data to the receiver 400 insynchronization with the audio clock generated from the carrier clockrecovered from the received encoded data, in accordance with a requestfrom the receiver 400. Accordingly, this enables the transmitter 300 toperform transmission processing effectively, that is, in accordance withthe processing capability of the receiver 400.

Furthermore, in the AV system 10 illustrated in FIG. 1, the transmitter300 (refer to FIG. 3) generates an audio clock by (dividing the carrierclock on the basis of the dividing ratio information obtained from thereceived encoded data. In this case, the division is performed on thebasis of the dividing ratio information transmitted from the externaldevice, making it possible to easily and properly generate the audioclock.

Furthermore, in the AV system 10 illustrated in FIG. 1, the receiver 400(refer to FIG. 3) transmits encoded data capable of clock recovery insynchronization with the carrier clock generated on the basis of thegenerated audio clock, to the transmitter 300 (refer to FIG. 3), andprocesses the audio data received from the transmitter 300 on the basisof the audio clock. Therefore, it is possible to perform high qualityaudio reproduction without supplying a transmission clock using a clocksignal line to the transmitter 300.

Furthermore, in the AV system 10 illustrated in FIG. 1, the receiver 400(refer to FIG. 3) includes encoded data for the dividing ratioinformation for obtaining an audio clock from the carrier Clock asencoded data capable of clock recovery to be transmitted to thetransmitter 300. Therefore, the transmitter 300 can obtain the audioclock by performing division on the carrier clock recovered from theencoded data on the basis of the dividing ratio information, making itpossible to generate the audio clock easily and appropriately.

Furthermore, in the AV system 10 illustrated in FIG. 1, the receiver 400(refer to FIG. 3) includes encoded data for the request for using anaudio clock generated from the recovered carrier clock as encoded datacapable of clock recovery to be transmitted to the transmitter 300.

Accordingly, the transmitter 300 can effectively perform transmissionprocessing of audio data based on the audio clock generated from therecovered carrier clock.

2. Modification

Note that the above embodiment is an exemplary case where the discplayer 11 (refer to FIG. 11) is illustrated as a specific example of thetransmitter 300, and the television receiver 12 (refer to FIG. 12) isfurther illustrated as a specific example of the receiver 400. However,the transmitter 300 and the receiver 400 are apparently not limited tothese.

Furthermore, the present technology can also be configured as follows.

(1) A transmission apparatus including:

an encoded data reception unit that receives encoded data capable ofclock recovery from an external device;

an audio clock generator that generates an audio clock on the basis of acarrier clock recovered from the received encoded data; and

an audio data transmission unit that transmits audio data to theexternal device in synchronization with the generated audio clock.

(2) The transmission apparatus according to (1),

in which the audio clock generator generates the audio clock by dividingthe carrier clock on the basis of dividing ratio information obtainedfrom the received encoded data.

(3) The transmission apparatus according to (1) or (2),

in which, when a request for using the audio clock generated on thebasis of the recovered carrier clock can be obtained,

the audio clock generator generates an audio clock on the basis of thecarrier clock recovered from the encoded data,

and

the audio data transmission unit transmits the audio data to theexternal device in synchronization with the generated audio clock.

(4) The transmission apparatus according to any of (1) to (3),

in which the audio data transmission unit transmits the audio data tothe external device through a first physical channel, and the encodeddata reception unit receives the encoded data from the external devicethrough a second physical channel.

(5) The transmission apparatus according to (4),

in which each of the first physical channel and the second physicalchannel is a physical channel using an optical cable.

(6) A transmission method including:

an encoded data reception step of receiving encoded data capable ofclock recovery from an external device;

an audio clock generation step of generating an audio clock on the basisof a carrier clock recovered from the received encoded data; and

an audio data transmission step of transmitting audio data to theexternal device in synchronization with the generated audio clock by anaudio data transmission unit.

(7) A reception apparatus including:

an audio clock generator that generates an audio clock;

an encoded data transmission unit that transmits encoded data capable ofclock recovery in synchronization with a carrier clock generated on thebasis of the generated audio clock to an external device;

an audio data reception unit that receives audio data from the externaldevice; and an audio data processing unit that processes the received

audio data on the basis of the generated audio clock.

(8) The reception apparatus according to (7),

in which the encoded data includes encoded data of dividing ratioinformation for obtaining the audio clock from the carrier clock, (9)The reception apparatus according to (7) or (8),

in which the encoded data includes encoded data of a request for usingan audio clock generated on the basis of the carrier clock.

(10) The reception apparatus according to any of (7) to (9),

in which the audio data reception unit receives the audio data from theexternal device through a first physical channel, and

the encoded data transmission unit transmits the encoded data to theexternal device through a second physical channel

(11) The reception apparatus according to (10),

in which each of the first physical channel and the second physicalchannel is a physical channel using an optical cable.

(12) A reception method including:

an audio clock generation step of generating an audio clock;

an encoded data transmission step of transmitting encoded data capableof clock recovery in synchronization with a carrier clock generated onthe basis of the generated audio clock to an external device;

an audio data reception step of receiving audio data by an audio datareception unit from the external device; and

an audio data processing step of processing the received audio data onthe basis of the generated audio clock.

(13) A transmission/reception system having a transmission apparatus anda reception apparatus mutually connected via a physical channel,

in which the transmission apparatus includes:

an encoded data reception unit that receives encoded data capable ofclock recovery from the reception apparatus;

an audio clock generator that generates an audio clock on the basis of acarrier clock recovered from the received encoded data; and

an audio data transmission unit that transmits audio data to thereception apparatus in synchronization with the generated audio clock,and

the reception apparatus includes:

an audio clock generator that generates an audio clock;

an encoded data transmission unit that transmits encoded data capable ofclock recovery in synchronization with a carrier clock generated on thebasis of the generated audio clock to the transmission apparatus;

an audio data reception unit that receives audio data from thetransmission apparatus; and

an audio data processing unit that processes the received audio data onthe basis of the generated audio clock.

REFERENCE SIGNS LIST

-   AV transmission system-   60 Main stream link-   70 Sub stream link-   104 CPU-   105 Internal bus-   106 Flash ROM-   107 SDRAM-   108 Remote control reception unit-   109 Remote control transmitter-   110 SATA interface-   111 BD drive-   112 Ethernet interface-   113 Network terminal-   115 MPEG decoder-   116 Graphic generation circuit-   117 Video output terminal-   118 Sound output terminal-   121 Display control unit-   122 Panel drive circuit-   123 Display panel-   124 Power supply unit-   125 Main stream link transmission unit-   126 Sub stream link transmission unit-   127 Sub stream link reception unit-   205 Antenna terminal-   206 Digital tuner-   207 MPEG decoder-   208 Video signal processing circuit-   209 Graphic generation circuit-   210 Panel drive circuit-   211 Display panel-   212 Sound signal processing circuit-   213 Sound amplification circuit-   214 Speaker-   220 Internal bus-   221 CPU-   222 Flash ROM-   223 SDRAM-   224 Ethernet interface-   225 Network terminal-   226 Remote control reception unit-   227 Remote control transmitter-   231 Display control unit-   232 Power supply unit-   233 Main stream link reception unit-   234 Sub stream link reception unit-   235 Sub stream link transmission unit-   236 Audio clock source-   300 Transmitter-   301 Audio source-   302 FIFO memory unit-   303 ASPU generator-   304 AAPU generator-   305 Lane frame generator-   306 Transmission unit of main stream link-   307 Reception unit of sub stream link-   308 CDR unit-   308 a Phase frequency detector-   308 b Loop filter-   308 c Voltage controlled oscillator-   308 d Data register-   309 Lane frame decoding unit-   310 ACMSW decoding unit-   311 Audio clock recovery unit-   311 a, 311 b, 311 c, 311 e Divider-   311 d PLL circuit-   400 Receiver-   401 Reception unit of main stream link-   402 Lane frame decoding unit-   403 ASPU decoding unit-   404 AAPU decoding unit-   405 Audio decoding unit-   406 Audio clock source-   407 Lane clock generator-   407 a Naud generator-   407 b, 407 c Counting unit-   407 d Latch unit-   407 e, 407 f Multiplier-   408 ACMSW generator-   409 Lane frame generator-   410 Transmission unit of sub stream link-   511 Scrambler-   512 8B/10B encoder-   513 Serializer-   514 Laser diode driver-   515 Laser diode-   521 Photodetector-   522 Amplifier-   523 De-serializer-   524 8B/10B decoder-   525 Descrambler-   601 Data packing unit-   602 VCR/ACR generator-   603 Frame generator-   604 Multi-stream constructor-   605 Channel mapper-   606 Channel de-mapper-   607 Multi-stream de-constructor-   608 Packet generator-   609 Data de packing unit-   610 Video/audio clock unit-   701 a, 701 b Data packing unit-   702 a, 702 b Frame generator-   703 a, 703 b Packet generator-   704 a, 704 b Data de-packing unit

The invention claimed is:
 1. A transmission apparatus comprising: anencoded data reception unit that receives encoded data including anaudio clock master switch packet capable of clock recovery from anexternal device, wherein the audio clock master switch packet isgenerated based on an audio clock source of the external device; anaudio clock generator that generates an audio clock on the basis of acarrier clock recovered from the received encoded data, wherein theaudio clock generator generates the audio clock by dividing the carrierclock on the basis of dividing ratio information obtained from the audioclock master switch packet of the received encoded data; and an audiodata transmission unit that transmits audio data to the external devicein synchronization with the generated audio clock, wherein the encodeddata including the audio clock master switch packet is received from theexternal device using a sub stream link, wherein the audio data istransmitted to the external device using a main stream link insynchronization with the generated audio clock that is generated on thebasis of the carrier clock recovered from the encoded data received fromthe external device using the sub stream link, wherein the audio data isdecoded for output by the external device based on the audio clocksource of the external device used to generate the audio clock masterswitch packet, and wherein the encoded data reception unit, the audioclock generator, and the audio data transmission unit are eachimplemented via at least one processor.
 2. The transmission apparatusaccording to claim 1, wherein, when a request for using the audio clockgenerated on the basis of the recovered carrier clock is obtained, theaudio clock generator generates an audio clock on the basis of thecarrier clock recovered from the encoded data, and the audio datatransmission unit transmits the audio data to the external device insynchronization with the generated audio clock.
 3. The transmissionapparatus according to claim 1, wherein the audio data transmission unittransmits the audio data to the external device through a first physicalchannel as the main stream link, and the encoded data reception unitreceives the encoded data from the external device through a secondphysical channel as the sub stream link.
 4. The transmission apparatusaccording to claim 3, wherein each of the first physical channel and thesecond physical channel comprises a physical channel using an opticalcable.
 5. A transmission method comprising: receiving encoded dataincluding an audio clock master switch packet capable of clock recoveryfrom an external device, wherein the audio clock master switch packet isgenerated based on an audio clock source of the external device;generating an audio clock on the basis of a carrier clock recovered fromthe received encoded data, wherein generating the audio clock comprisesdividing the carrier clock on the basis of dividing ratio informationobtained from the audio clock master switch packet of the receivedencoded data; and transmitting audio data to the external device insynchronization with the generated audio clock by an audio datatransmission unit, wherein the encoded data including the audio clockmaster switch packet is received from the external device using a substream link, wherein the audio data is transmitted to the externaldevice using a main stream link in synchronization with the generatedaudio clock that is generated on the basis of the carrier clockrecovered from the encoded data received from the external device usingthe sub stream link, and wherein the audio data is decoded for output bythe external device based on the audio clock source of the externaldevice used to generate the audio clock master switch packet.
 6. Areception apparatus comprising: an audio clock generator that generatesan audio clock master switch packet based on an audio clock source ofthe reception apparatus; an encoded data transmission unit thattransmits encoded data including the audio clock master switch packetcapable of clock recovery in synchronization with a carrier clockgenerated on the basis of the generated audio clock to an externaldevice; an audio data reception unit that receives audio data from theexternal device; and an audio data processing unit that processes thereceived audio data on the basis of the generated audio clock, whereinthe audio clock master switch packet of the encoded data includesencoded data of dividing ratio information for obtaining the audio clockfrom the carrier clock, wherein the encoded data including the audioclock master switch packet is transmitted to the external device using asub stream link, wherein the audio data is received from the externaldevice using a main stream link in synchronization with the generatedaudio clock that is generated on the basis of the carrier clockrecovered from the encoded data transmitted to the external device usingthe sub stream link, wherein the audio data is decoded for output by thereception apparatus based on the audio clock source of the receptionapparatus used to generate the audio clock master switch packet, andwherein the audio clock generator, the encoded data transmission unit,the audio data reception unit, and the audio data processing unit areeach implemented via at least one processor.
 7. The reception apparatusaccording to claim 6, wherein the audio clock master switch packet ofthe encoded data includes encoded data of a request for using an audioclock generated on the basis of the carrier clock.
 8. The receptionapparatus according to claim 6, wherein the audio data reception unitreceives the audio data from the external device through a firstphysical channel as the main stream link, and the encoded datatransmission unit transmits the encoded data to the external devicethrough a second physical channel as the sub stream link.
 9. Thereception apparatus according to claim 8, wherein each of the firstphysical channel and the second physical channel comprises a physicalchannel using an optical cable.
 10. A reception method comprising:generating an audio clock and an audio clock master switch packet basedon an audio clock source of a reception apparatus; transmitting encodeddata including the audio clock master switch packet capable of clockrecovery in synchronization with a carrier clock generated on the basisof the generated audio clock from the reception apparatus to an externaldevice; receiving audio data from the external device; and processingthe received audio data on the basis of the generated audio clock,wherein the audio clock master switch packet of the encoded dataincludes encoded data of dividing ratio information for obtaining theaudio clock from the carrier clock, wherein the encoded data includingthe audio clock master switch packet is transmitted to the externaldevice using a sub stream link, wherein the audio data is received bythe reception apparatus from the external device using a main streamlink in synchronization with the generated audio clock that is generatedon the basis of the carrier clock recovered from the encoded datatransmitted to the external device using the sub stream link, andwherein the audio data is decoded for output by the reception apparatusbased on the audio clock source of the reception apparatus used togenerate the audio clock master switch packet.
 11. Atransmission/reception system having a transmission apparatus and areception apparatus mutually connected via a physical channel, whereinthe transmission apparatus includes: an encoded data reception unit thatreceives encoded data including an audio clock master switch packetcapable of clock recovery from the reception apparatus, wherein theaudio clock master switch packet is generated based on an audio clocksource of the reception apparatus; an audio clock generator thatgenerates an audio clock on the basis of a carrier clock recovered fromthe received encoded data, wherein the audio clock generator generatesthe audio clock by dividing the carrier clock on the basis of dividingratio information obtained from the audio clock master switch packet ofthe received encoded data; and an audio data transmission unit thattransmits audio data to the reception apparatus in synchronization withthe generated audio clock, and the reception apparatus includes: anaudio clock generator that generates an audio clock based on the audioclock source of the reception apparatus; an encoded data transmissionunit that transmits the encoded data including the audio clock masterswitch packet capable of clock recovery in synchronization with acarrier clock generated on the basis of the generated audio clock to thetransmission apparatus; an audio data reception unit that receives theaudio data from the transmission apparatus; and an audio data processingunit that processes the received audio data on the basis of thegenerated audio clock, wherein the transmission apparatus receives theencoded data including the audio clock master switch packet from thereception apparatus using a sub stream link, wherein the transmissionapparatus transmits the audio data to the reception apparatus using amain stream link in synchronization with the generated audio clock thatis generated on the basis of the carrier clock recovered from theencoded data received from the reception apparatus using the sub streamlink, wherein the audio data is decoded for output by the receptionapparatus based on the audio clock source of the reception apparatusused to generate the audio clock master switch packet, and wherein theencoded data reception unit, the audio clock generator, and the audiodata transmission unit of the transmission apparatus and the audio clockgenerator, the encoded data transmission unit, the audio data receptionunit, and the audio data processing unit of the reception apparatus areeach implemented via at least one processor.
 12. The transmissionapparatus according to claim 1, wherein the dividing ratio informationincludes Maud and Naud, wherein Maud is a count value of a video clock,and wherein Naud is a count interval of the generated audio clock. 13.The transmission apparatus according to claim 1, wherein the carrierclock is generated by the external device based on an audio clockgenerated by the audio clock source and a video clock.